Today (June 10, 2021) at 10:00 UTC the Sailfish SDK 3.5 release was published to all users. Please, check out the in depth release notes from original post.
The installers for this release of the SDK are now available at http://sailfishos.org/wiki/Application_SDK#Latest_SDK_Release.
If you have an older release of the SDK, you should see an update notification in the Sailfish IDE.
If you have any questions, feel free to either write it up here in https://forum.sailfishos.org/ or send an e-mail to developer-care at jolla.com.
Happy hacking,
Jolla SDK Team